Composites of elastic and nonelastic materials have been made by bonding nonelastic materials to elastic materials in a manner that allows the entire composite to stretch or elongate so they can be used in garment materials, pads, diapers and personal care products where elasticity may be desired.
In one such composite material, a nonelastic material joined to an elastic sheet while the elastic sheet is in a stretched condition so that when the elastic sheet relaxed, the nonelastic material gathers between the locations where it is bonded to the elastic sheet. The resulting composite elastic material is stretchable to the extent that the nonelastic material gathered between the bond locations allows the elastic sheet to elongate. An example of this type of composite material is disclosed, for example, by U.S. Pat. No. 4,720,415 to Vander Wielen et al., issued Jan. 19, 1988.
In many applications, composite materials of this type are adapted to stretch and recover in only one direction such as, for example, the machine direction. Thus, the elastic component of the composite does not have to be isotropic. That is, the elastic component need not have the same stretch and recovery properties in every direction. Desirably, the elastic component would have the required stretch and recovery properties in only the direction that the gathered inelastic material allows the composite to stretch. For example, if filaments, fibers and/or strands of an elastic material were oriented in only one direction, a relatively smaller amount of elastic material could be used to provide certain levels of elastic properties, such as tension, in that one direction than if the elastic material was isotropic. Reducing the amount of elastic material in the composite would generally reduce its cost. This is an important consideration for composite elastic materials which are intended to be components single use or limited use products such as, for example, disposable personal care products.
However, conventional elastic materials such as, for example, elastic nonwoven fibrous webs and elastic tend to be relatively isotropic and less efficient for materials that stretch and recover in only one direction. Although certain composite materials that contain parallel rows of elastic filaments or strands are known to provide stretch and recovery generally in one direction, these materials are not well suited to high-speed manufacturing processes because of the difficulties of applying individual elastomeric filaments or strands to an inelastic, gatherable material.
For example, U.S. Pat. No. 3,468,748 discloses a nonwoven fabric having machine direction elasticity which contains at least one fibrous web and a plurality elastic cords, strings, bands, etc., which is joined to the fibrous web while the elastic material is stretched. Upon release of the stretching force, the elastic material contracts from its extended condition and creates puckers in the material. U.S. Pat. No. 3,575,782 discloses an elastic material which contains partially extended spaced elastic yarns sealed between two gathered fibrous webs. According to the patent, elastic yarns are stretched, joined to the fibrous webs with a binder and then passed through a drying oven. Tension on the elastic yarn relaxed and more heat is applied to cause the elastic yarns to retract or shrink, creating a shirred elastic material.
Other patents disclose reinforced textile matrices and stabilized continuous filament webs in which threads or molecularly oriented continuous filaments are stabilized in a substantially parallel relationship. For example, U.S. Pat. No. 4,680,213 discloses a reinforced textile matrix and U.S. Pat. No. 4,910,064 discloses a substantially parallel array of molecularly oriented continuous filaments stabilized by meltblown fibers to create a coherent nonwoven fibrous web.
However, there is still a need for an inexpensive composite elastic material having stretch and recovery in only one direction, which is suited for high-speed manufacturing processes and which contains an elastic component that provides the desired elastic properties to the composite only in the one direction of stretch and recovery.